Drying apparatus for drying moist organic or inorganic materials



T. ONARHElM Feb. 11, 1969 DRYING APPARATUS FOR DRYING MOIST ORGANIC 0R INORGANIC MATERIALS Filed Feb. 21, 1967 INVENTOR:

United States Patent U.S. c1. 165-87 Int. Cl. F28f 5/04, I/26, 9/00 2 Claims ABSTRACT OF THE DISCLOSURE A pair of hollow cylinders carrying disc shaped heating members are arranged side by side within a drying chamber with their axes of rotation extending from the inlet to the outlet end. The spacing between the axes of rotation is less than the diameter of said heating members.

The present invention relates to a drying apparatus, preferably steam heated, for drying moist organic or inorganic materials, of the kind comprising a stationary, housing with a substantially horizontal drying chamber enclosed by a hollow jacket and rotary heating members arranged within said chamber.

In applicants prior British patent specification No. 789,439 a steam heated drying apparatus of substantially the same kind as the present one is shown, many of the details being disclosed in said patent. The steam heated drying apparatus of the British patent specification comprises a cylindrical drying chamber in which a hollow steam conveying cylinder is mounted within the drying chamber for rotation about an axis coinciding with or parallel to the longitudinal axis of the drying chamber.

The hollow cylinder carries a plurality of outwards protruding hollow, ring or disc shaped members to which a heating fluid, preferably steam, is supplied and discharged through the hollow cylinder.

By means of the ring or disc shaped heating members of the hollow cylinder and the enclosing of the steam jacket of the drying chamber, a good concentration of heating area per unit of volume has been obtained. However, since the hollow cylinder extends in the longitudinal direction of the drying chamber, the axial length of the apparatus as a whole may be inconvenient for applications when very moist materials are to be treated. It will often be so, for instance when the drying apparatus is to be installed on board a ship, such as a trawler, that the space available in the axial direction may be limited, although there is ample space in a lateral direction. Increasing the diameter of the apparatus as a whole will not give the desired result, since the heating area per unit of volume will be decreased.

It is an object of the present invention to provide an arrangement enabling the heating capacity per unit of length to be considerably increased, whereby the axial length of the apparatus can be considerably reduced.

A further object of the present invention is to obtain a drying apparatus in which inlet and outlet sluices can be arranged at the inlet and the outlet end, whereby introduction and discharge of material can take place without interfering with vacuum conditions within the drying chamber. Hereby, the materials can be subjected to a continuous drying operation under sub-atmospheric pressure, thereby increasing the drying effect.

According to the present invention, the drying chamber contains at least two such rotatable hollow cylinders the rotational axes of which extend parallel to each other from the inlet to the outlet end of the drying chamber, and the spacing between said axis of rotation being less than the ICC total diameter of the ring or disc shaped heating members carried on said hollow cylinders. Hereby, the ring or disc shaped heating members of one hollow cylinder will protrude into the space between two adjacent ring or disc shaped members on the other rotary cylinder.

According to a further feature of the present invention, scraper means are arranged on each rotary cylinder for scraping ofi material which may tend to stick to the surface of the other cylinder and to the inner wall of the heating jacket. Although such scraper means are known in the art, for instance from the British patent specification mentioned above, it has appeared that they in the apparatus according to the present invention also increase the drying efiiciency of the apparatus as a whole, since they tend to create a whirling motion in the area where the heating members of the rotary cylinders overlap.

Further features of the invention appear from the following description and the appended claims.

The invention will now be explained to a greater detail with reference to the appended drawing illustrating two embodiments, wherein:

FIG. 1 is an axial sectional view of the steam heated drying apparatus according to the invention, in an embodiment comprising two rotors arranged one above the other.

FIG. 2 is a cross sectional view of the heating apparatus according to FIG. 1.

FIG. 3 is a cross sectional view of a heating apparatus comprising two rotors arranged side by side.

In the embodiment illustrated in the FIGS. 1 and 2 the steam dryer comprises a housing 10' forming the drying chamber 10a for the dryer and being provided with a steam jacket 11 for heating the inner wall of the housing 10 and the drying chamber. The steam jacket 11 may as known per se be divided into sections (not shown) which are individually charged with steam through supply means, not shown.

In the embodiment illustrated in FIGS. 1 and 2 the housing provided is at the top, at one end, with an inlet 12 for the supply of material to the drying chamber 10a, and a laterally directed discharge opening 13a with a discharge channel 14 is arranged at the opposite end of the housing in the upper portion thereof. FIGS. 1 and 2 further comprise two rotatable heating members 15a and 15b arranged vertically one above the other. The heating members are driven by an electric motor 16, preferably via a suitable transmission. This heating member comprises a hollow stub shaft 17 mounted in a bearing 18 in one end of the housing. The stub shaft 17 is secured to a hollow cylinder 19 extending over the entire length of the housing 10 and is secured in its other end to a second stub shaft 20 mounted in a bearing 21.

A plurality of hollow disc shaped members 22 are welded to the outer cylindrical face of the cylinder 18. These members may be obtained by shaping two annular plates into truncated cones and arranging them with their base lines engaging toward each other, whereupon the truncated cones are welded together at their base lines. The circular central openings are then welded to the cylindrical wall of the hollow cylinder 19.

It will appear that the outer periphery of the members 22 are spaced from the inner wall of the housing, whereby the mass received within the drying chamber may advance through the outer passage defined by the inner wall of the housing and the periphery of the members 22.

A plate 23 is secured to each of the circular heating members 22 with its plane parallel to the axis of the cylinder. Said plates are preferably arranged along a helical path on successive members in the longitudinal direction of the rotatable heating member. This feature enables a certain transportational effect to be obtained although the planes of said plates are parallel to the axis of the cylinder. However, for some applications it may be desired to arrange such plates under an oblique angle to the longitudinal direction if it is desired to obtain a quicker or slower advancing effect upon the material within the drying chamber.

Each of the hollow heating members 15a and 15b are preferably supplied with steam and condensate removed in the same way as described in the British patent specification No. 789,439 mentioned above, reference being had to this patent regarding the specific details of the means for the supply of live steam and discharge of condensate.

At the inlet end the lower hollow cylinder 15a is provided with disc shaped agitating and scraping members 35 carried by supporting arms 36 secured to the hollow cylinder. Corresponding agitating and scraping members 37 are carried by supporting arms 35 secured to the upper hollow cylinder 15b and the outlet end of the drying chamber. The latter members 37 also serve to bring a certain amount of the dry material up to the outlet opening through which the dry material leaves the drying chamber.

Referring now to FIG. 3, it will appear that the rotatable heating members comprising hollow cylinders carrying disc shaped members 22 are not arranged as upper and lower cylinders but side by side in a housing having an elongated cross section in the lateral direction. This embodiment may be convenient in cases where the space in a vertical direction is occupied by equipment for pre-treating the materials before they enter into the drying chamber.

Scraper means 39a of FIG. 2 and 39b of FIG. 3 may be secured to the inner wall of the housing 10. Such scraper means 39a, 39b will serve to scrape off material that may stick to the outer face of the hollow cylinder. However, for most applications such additional scraping means will be superfluous, since the members 35 and 37 normally will be sufficient to keep the heating faces clean.

In the embodiment of FIGS. 1 and 2 a discharge opening 41a for vapours and drying air is arranged at the top of the housing 10 near the outlet end. A similar discharge opening 41b is located at the side of the housing 10 in FIG. 3. The discharge opening 13b is in FIG. 3 located beneath the discharge opening 41b.

In the embodiment of FIGS. 1 and 2 the housing 10 has a rounded bottom and a square top. Because of this, passages 42a and 42b will be formed for easier passage of vapour and drying air, which may be introduced into the drying chamber for assisting in the drying operation. These passages 42a and 42b are defined by the upper side wall portions 43a and 43b and the flat top 44a of the housing. Similar passages 42c and 42d for vapour and air are formed in FIG. 3, one passage 420 being obtained by arranging a similar flat portion 44b of the top of the housing, whereas the other one will be formed in the space between the rotors. In the arrangement of FIG. 3, this portion will not be filled with material, since the level within the drying chamber will be lower.

Although only two rotatable heating members are shown, it is obvious that a number of such parallel heating members may be arranged side by side or one above the other in different arrangements, if an increased efficiency is desired.

What I claim is:

1. A drying apparatus for drying moist materials, comprising a stationary housing with a substantially horizontal drying chamber enclosed by a hollow jacket, said jacket having an inlet and an outlet for the passage of the treated materials, and rotatable heating members within said chamber, such members comprising a hollow cylinder and a plurality of outwards protruding hollow disc shaped members on said cylinder to which heating fluid is supplied and discharged via the hollow cylinder, at least some of said disc shaped members including plate means Secured at the outer periphery of said disc shaped members and arranged to secure a transporting effect in the axial direction of the hollow cylinder, the rotatable heating members being at least two in number and having rotational axes which extend parallel to each other from an inlet to an outlet end of said drying chamber, the spacing between said axes of rotation being less than the total diameter of the disc shaped members carried on said hollow cylinders, whereby the disc shaped heating members of one hollow cylinder will protrude into the space between two adjacent disc shaped members on the adjacent hollow cylinder and said plate means constitute scraping means for scraping material which may stick to the surface of the hollow cylinder and to the inner wall of the jacket and agitating means on said cylinders for agitating material in the area between adjacent hollow cylinders.

2. Apparatus as claimed in claim 1 wherein said agitating means comprises plate members secured to said cylinders and extending towards the surface of the jacket and the surface of an adjacent cylinder in the region of said inlet and outlet.

References Cited UNITED STATES PATENTS 2,883,163 4/1959 Solheim 16587 3,263,748 8/1966 Jemal et a1 165-87 FOREIGN PATENTS 789,439 1/1958 Great Britain.

KENNETH W. SPRAGUE, Primary Examiner.

US. Cl. X.R. l94; 34-183 

